Thank you for your question. Feeding from potato leafhoppers can cause marginal necrosis but I have never seen it to this severe of an extent. Are you noticing any small insects on the leaves?

This could also be sign of a nutrient toxicity issue - overabundance of nutrients like boron can accumulate at the leaf margins during transpiration, causing tissue death. Have you performed a soil test for the area? What fertilizer has been used on the potatoes?

This does not stand out to me as a disease issue. However, if we can't identify an abiotic cause, it might pay to send in a sample to the MSU diagnostic lab on campus to test for pathogens: https://www.canr.msu.edu/pestid/submit-samples/

No visible insects.  I used bone emal and a simple organic 5-10-10 fertilizer when I planted.  When you suggested sending in a sample where you referring to a soil sample of the plant itself?

I was referring to sending a plant sample in to the diagnostic lab to determine if it is a disease. If we can identify the disease (or rule it out), we can determine the appropriate control measures. 

A soil sample sent to a soil testing lab could help determine if there is an overabundance or deficiency of some nutrient that is causing the issues. 

Are you growing any other crops in the same location that are showing similar symptoms? How long ago did the symptoms start? Do the roots/tubers look healthy? 

Thank yo for your response.  I will take a sample in for testing.   I have green beans on one side of the potatoes, corn on the other.  and tomatoes on the other side of the corn.  So far they all look good.  The symptoms started about two weeks ago.  The tubers that I have dug up look fine for this stage of growth.